Various signal processing systems may utilize comb filtering, which generally refers to signal processing that separates signals with spectra that are interleaved in the frequency domain in a pattern that may resemble teeth of a comb. For example, video-processing systems may utilize comb filtering to separate chroma information from luma information in composite video signals.
Various systems and methods exist for comb filtering, including two-dimensional and three-dimensional comb filtering. Two-dimensional comb filtering may involve, for example, performing comb filtering on a current video signal and another video signal from the same video field as the current video signal. Two-dimensional comb filtering may process a current video signal from a current video line with a second signal from a video line in the same video field that is vertically adjacent to the current video line and that corresponds horizontally to the current video signal. Three-dimensional comb filtering may include, for example, performing comb filtering on a current video signal from a current video frame and another video signal from a different video frame that corresponds spatially to the current video signal. In the following discussion, “three-dimensional comb filtering” generally refers to comb filtering using at least two signals that are not from the same video field.
In video processing systems that utilize two-dimensional and three-dimensional comb filtering, various phenomena in the processed video signals may cause one of two-dimensional filtering and three-dimensional filtering to be superior to the other. For example, when performing three-dimensional comb filtering on a current signal, significant motion between the current frame and the previous frame (or other different frame) may result in a poor frame comb. In such a situation, it may be preferable for the video processing system to at least temporarily utilize two-dimensional comb filtering instead of three-dimensional comb filtering in processing the current signal.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with the present invention as set forth in the remainder of the present application with reference to the drawings.